aLIGO LHO Logbook

H1 SUS (CDS, SUS)

rahul.kumar@LIGO.ORG - posted 09:42, Thursday 18 December 2025 - last comment - 11:00, Thursday 18 December 2025(88588)

HAM1: JM3 (JAC) and PM1 Satamps replaced (in LVEA), JM2 and JM3 cables swapped (in CER)

Fil, Rahul

This morning we replaced the unmodified Satamps for JM3/PM1 (both TT suspension) with the modified version - as per alog 88584. Given below are the details,

Old satamp s/n - S1200173

New Satamp s/n - S2500407

The adc counts of the bosems on JM3 and PM1 have dropped by 25% approximately due to the above change, hence we will have to compensate that on the filter side (Oli is currently on it).

Also, we have swapped the cables for JM2 (mount) with JM3 (SUS TT) in the CER - as per alog 88584, this is now consistent with the wiring diagram.

Comments related to this report

ryan.crouch@LIGO.ORG - 10:09, Thursday 18 December 2025 (88589)

Link

A plot of some OSEM values before and after the satamp swap for PM1.

Images attached to this comment

oli.patane@LIGO.ORG - 11:00, Thursday 18 December 2025 (88593)

Link

Here's the characterization data and fit results for S2500407, assigned to JM3 / PM1 M1's ULURLLLR OSEMs.

This sat amp is a US 8CH sat amp, D1002818 / D080276. The data was taken per methods described in T080062-v3, using the diagrammatic setup shown on PAGE 1 of the Measurement Diagrams from LHO:86807.

The data was processed and fit using ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Scripts/
plotresponse_S2500407_H1_JM3PM1_M1_ULLLURLUR_20250915.m

Explicitly, the fit to the whitening stage zero and pole, the transimpedance feedback resistor, and foton design string are:

`Optic`	`Stage`	`Serial_Number`	`Channel_Number`	`OSEM_Name`	`Zero_Pole_Hz`	`R_TIA_kOhm`	`Foton_Design`
`JM3`	`M1`	`S2500407`	`CH1`	`UL`	`0.0927:5.07`	`-121`	`zpk([5.07],[0.0927],1,"n")`
			`CH2`	`UR`	`0.0949:5.18`	`-121`	`zpk([5.18],[0.0949],1,"n")`
			`CH3`	`LL`	`0.0949:5.19`	`-121`	`zpk([5.19],[0.0949],1,"n")`
			`CH4`	`LR`	`0.0955:5.22`	`-121`	`zpk([5.22],[0.0955],1,"n")`
`PM1`	`M1`		`CH5`	`UL`	`0.0931:5.09`	`-121`	`zpk([5.09],[0.0931],1,"n")`
			`CH6`	`UR`	`0.0942:5.15`	`-121`	`zpk([5.15],[0.0942],1,"n")`
			`CH7`	`LL`	`0.0935:5.105`	`-121`	`zpk([5.105],[0.0935],1,"n")`
			`CH8`	`LR`	`0.0969:5.29`	`-121`	`zpk([5.29],[0.0969],1,"n")`

The attached plot and machine readable .txt file version of the above table are also found in ${SusSVN}/trunk/electronicstesting/lho_electronics_testing/satamp/ECR_E2400330/Results/
2025-09-15_USDualSatAmp_S2500407_D080276-v3_fitresults.txt

Per usual, R_TIA_kOhm is not used in the compensation filter -- but after ruling out an adjustment in the zero frequency (by zeroing the phase residual at the lowest few frequency points), Jeff nudged the transimpedance a bit to get the magnitude scale within the ~0.25%, shown in the attached results. Any scaling like this will be accounted for instead with the absolute calibration step, i.e. Side Quest 4 from G2501621, a la what was done for PR3 and SR3 top masses in LHO:86222 and LHO:84531 respectively.